MgCl2.alcohol adducts and their use in the preparation of catalyst components for the polymerization of olefins is well known in the art.
Catalyst components for the polymerization of olefins, obtained by reacting MgCl2.nEtOH adducts with halogenated transition metal compounds, are described for example in U.S. Pat. No. 4,399,054. The adducts are prepared by emulsifying the molten adduct in an immiscible dispersing medium and quenching the emulsion in a cooling fluid to collect the adduct in the form of spherical particles.
In WO2009/80568 are disclosed magnesium chloride based adducts having a specific range of alcohol content and containing a specific amount of inorganic particles having a certain dimensional range are able to generate catalyst components with high polymerization activity and enhanced morphological stability. Specifically, the said document disclosed spherical adducts comprising a MgCl2, an alcohol ROH in which R is a C1-C10 hydrocarbon group, present in a molar ratio with MgCl2 ranging from 0.5 to 5 and less than 5% wt, based on the total weight of the adduct, of a solid inorganic compound selected from oxides or hydroxides of Si, Al, Mg, Ti and mixtures thereof. The so obtained supports led to the preparation of catalysts having improved morphological stability in terms of polymer breakages. However, by carrying out further experiment the applicant realized that the bulk density of the polymer was substantially negatively impacted.